Products to try or avoid? PWM Flicker and Temporal Dithering Testing

I've read users observing thin white lines in between pixels on certain displays. I don't notice them on my 7i or MBP but I remember seeing them on an older model Ryzen Legion laptop (don't know the laptop model panel unit). This reviewer calls it a "rastering effect".

https://www.reddit.com/r/thinkpad/comments/qxxtoq/thinkpad_x13_gen_2_amd_initial_initial/

There is a display lottery, and I lost it. Mine has the InfoVision M133NW4J R3, and it’s really bad. Out of the box, it has a warm/reddish cast, though a calibrated color profile may help. It also has a weird rastering effect, where you can see faint lines between the rows of pixels when you get moderately close to the panel. Looking at it with a 20x loupe, it seems that the space between rows of pixels is slightly further apart than between columns.

simplex

using the monitor settings not using CRU.

So I was interested in how light polarization might affect eyestrain and I tried some tracing paper in front my LG display. Looking through my polarized sunglasses I see no darkening effect however which why I orient the glasses. This means no more polarized light. The visibility is not too good for fine detailed work but passable only if you can get the paper fully pressed against the screen.

https://ledstrain.org/d/1421-tracing-paper

I found this research on smartphone light polarization (circular versus linear) on eye symptoms. Not sure about the conclusions of that paper but relevant to some observations on this forum. For myself, it seems that I'm not too sensitive (humans are supposed to be not sensitive at all to polarization?) to either type of polarization. Some iPhones are circularly polarized and so is my M2 MacBook Pro Touch Bar laptop.

Comparison of the influence of light between circularly polarized and linearly polarized smartphones on dry eye symptoms and asthenopia

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9010255/

PSA Update!

My LG 27gp95r-b is showing fainting horizontal banding across the entire width of the screen. Still too early to say if this causes increased eyestrain as I have to be very close to the screen to see it so it went undetected during my several months of ownership so far. This is an ips UHD rez 144hz monitor with 8 bit + FRC dithering. Hopefully this is not a widespread QC issue.

As some of you are considering trying older lenovo windows/linux laptops, I going to start a list here of potential replacement display panels for ThinkPad T480 and/or T480s that may work for some eyestrain wise.

1. https://www.panelook.com/LM140LF1F02_Panda_14.0_LCM_overview_48911.html (144hz refresh rate for a thinkpad!)
2. https://www.panelook.com/N140HCG-GQ2_Innolux_14.0_LCM_overview_41388.html (This is a low power IGZO FHD display for better battery life, IGZO means indium gallium zinc oxide as semiconductor material)
3. https://www.panelook.com/R140NWF5_R6_IVO_14.0_LCM_overview_36125.html (matte FHD touch screen, 6 bit color so not recommended for dithering reduction)
4. https://www.panelook.com/B140QAN02.0_AUO_14.0_LCM_overview_37246.html (hdr wqhd glossy)
5. https://www.panelook.com/B140QAN02.3_AUO_14.0_LCM_overview_33893.html (Non-hdr wqhd matte, what I am using in T480s)
6. https://www.panelook.com/LP140QH2-SPB1_LG%20Display_14.0_LCM_overview_40282.html (I prefer number 5 to this which came with my T480s)
7. https://www.panelook.com/N140HCA-EAB_Innolux_14.0_LCM_parameter_30063.html (has PWM)

How to guide:

https://forum.thinkpads.com/viewtopic.php?t=127439

https://www.ristrettorambles.com/upgrading-settling-into-the-thinkpad-t480/

https://www.ifixit.com/Device/Lenovo_ThinkPad_T480

https://www.ifixit.com/Device/Lenovo_ThinkPad_T480s

One thing to note is whether your machine comes with 40 pin or 30 pin cable and the eDP version and number of lanes. You may also have to use a pinout converter with one compatible with your chosen panel. When I replaced the panel on the T480s, the cable length was a just barely enough to reach the location of the slot on the panel. Another aspect to check is if you are using narrow or regular pitch pins. If you get a T480 the comes with a FHD touch display, it will greatly limit your options as to what panels can be swapped out without tinkering with eDP pinout adapters and motherboard to panel cables.

Resources for understanding pinouts and cables:

https://hackaday.io/project/179868-all-about-laptop-display-reuse/log/209701-common-edp-laptop-panel-pinouts

https://www.reddit.com/r/thinkpad/comments/uw0tit/t480s_from_fhd_touch_to_non/

https://old.reddit.com/r/thinkpad/comments/up3bql/seeking_advice_for_p14s_screen/

https://www.reddit.com/r/thinkpad/comments/i9oqr1/comment/g4fm42k/?rdt=45559 (see 30-pin normal eDP cable FRU 01YR501)

https://www.reddit.com/r/thinkpad/comments/v8tf2n/t480_screen_buying_advice_in_eu/?rdt=53836

Pin Pitch Converter Example

simplex

It doesn't look to me to be vertical green lines but white lines or spaces between horizontal rows. See this:

https://www.dropbox.com/scl/fi/apr1qfjvta6m17a9xvy30/IMG_20240620_093854.jpg?rlkey=12w5qeab6pc67pxmndzjb5bm0&st=kaa8xjgw&dl=0

Ignore the rainbow moire but notice the lines in the lighter parts in the trees. And this seems to be a static artifact. Panel degradation?

simplex

Nothing is different on video as it is static and not flickering. Yes, it is even easier to see with naked eye. This is third time I've seen this. First on a legion 5 amd laptop, the NEC EA271U-BK monitor, and now this LG gaming monitor.

simplex

The one I have listed in my original post for this discussion in the table: LG 27gp95r-b

I still need to find the specific panel model. It was not present or maybe as noticeable when brand new out of the box only a few months ago.

Edit update:

The horizontal lines are what's shown in these videos expect mine is less noticeable.

https://www.youtube.com/watch?v=2agVKO-Ihkk

https://www.youtube.com/watch?v=1FcM1cb34Uc

simplex
I have no idea. Need to find their datasheet.

PWM waveform at 0% and 100% brightness using thorlabs pda100a2 detector. 20dB gain setting on photodetector produces this waveform. Close to flat at 0dB gain setting.

Same photodetector 20dB gain settings but for legion 7i laptop and samsung s10+ (both at max panel brightness) Photodetector placed close up to panel with no interference from ambient artificial light.

Samsung s10+

Legion 7i 2023 laptop

simplex

I use legion 7i everyday with no issues (always set to 240hz refresh rate and linux mint). As I said before, I don't use the s10+ as main phone only for testing screens and the s10+ does give me strain after about half hour of use. Others seem to not tolerate the 7i.

xiaomi 12s ultra at max brightness and "dc dimming" enabled in developer settings (measured using thorlabs pda100a2)